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Sylvie Duhot

Non local electronic transport in superconductor hybrid

Published on 3 October 2008
Thesis presented October 03, 2008

In this thesis, we study various hybrid structures with superconducting parts.
The first chapter analyzes non local transport in normal metal (N) - superconductor (S) - normal metal structures. We consider one dimensional model for the N-S-N junctions using either the Blonder-Tinkham-Klapwijk method, or the Green's functions techniques. We find that non local transport can be enhanced by multiple scattering processes in the normal regions in a similar way as in the phenomenon of “reflectionless tunnelling”.
In the second chapter, we consider a nanoscale SQUID formed of a carbon nanotube coupled to superconducting electrodes. Non local processes decrease the critical current and introduce sample to sample fluctuations in the current-phase relation.
In the third chapter, we study the correlations of current fluctuations in superconducting multiterminal structures with semiclassical Boltzmann-Langevin theory. The multiple Andreev reflections can give a change of sign in crossed correlations for certain range of parameters.
In the last chapter, we analyze hybrid systems involving superconductors and charge density wave (CDW) compounds. We find that the Cooper pair can penetrate in the CDW just on Fermi wavelength. So, the S-CDW-S junction does not transport supercurrent.

Theory, Superconductor, Non local transport, Noise, Cross correlation

On-line thesis.